1. Field of the Invention
This invention relates to a toner for the development of an electrostatic latent image. More particularly, this invention relates to an electrostatic latent image-developing toner to be used for the development of an electrostatic latent image in electrophotography, electrostatic recording, and electrostatic printing.
2. Description of the Prior Art
The development of an electrostatic latent image in electrophotography, electrostatic recording, and electrostatic printing is effected by causing a triboelectrified toner to be adsorbed electrostatically to an electrostatic latent image formed on a photosensitive material thereby visualizing the latent image. As means of electrifying the toner to be used in this development of an electrostatic latent image, the two-component developing method is known to effect the electrification by mixing the toner with a substance generally called a carrier for through dispersion therein and consequently imparting an electric charge to the toner and the one-component developing method to effect the electrification by establishing contact between the toner and a developing sleeve or a toner regulating blade.
Heretofore, the dry toner has been generally manufactured by a method which comprises mixing, melting, and blending a pigment such as carbon black in thermoplastic resin thereby preparing a homogeneous dispersion and then pulverizing the dispersion by the use of a suitable pulverizing device into a powder having a particle diameter proper for a toner. As other methods for the manufacture of the dry toner, those represented by the suspension polymerization method and the suspension pelletization method which effect the pulverization of the dispersion in a wet state have been also known. The suspension polymerization method, as disclosed in Japanese Patent Publications 36-10,231, 43-10,799, and 53-14,895, for example, effects the pulverization by suspending a polymerization composition having a polymerizing monomer, a polymerization initiator, and a coloring agent as its components in a non-solvent type medium and polymerizing the resultant suspension. The suspension pelletization method attains the pulverization by blending a synthetic resin with a coloring agent and other components, melting the resultant mixture, and suspending the molten mixture in a non-solvent type medium.
In recent years, in the copier and printer sectors of electrophotography, the toner has come to be urged to fulfill various functions concerning coloration of images, reduction of particle size and compaction of particle diameter distribution for the sake of image quality, expedition of the operation of image formation, enhancement of the reliability of quality, etc. In reply to these demands, techniques for uniformly attaching or fixing minute particles fulfilling the required functions to or on the surface of the toner particles have been proposed.
The toners having the functional minute particles uniformly attached to or fixed on their surface, however, fail to manifest the required functions to a fully satisfactory extent or, in spite of fully satisfactory initial functions, fail to retain the functions stably for a long time.